Personal Horror Story

I need some advice on my personal residence (in California) and an issue I am going through. Long story as short as I can, I purchased this residence about 2 years ago with 4 other people. Each person owns 25% with one of the 25% portions being a husband and wife couple. Unfortunately, the couple went through a nasty divorce which is now final. The husband has gone completely MIA, however he is still paying for his portion of the mortgage. All 5 parties have sign on the loan and mortgage. We originally signed a back of the napkin agreement with one another for 2 years. At the end of 2 years we would discuss what to do with the property. Now that we are coming up on 2 years 4 of the 5 people involved would like to sell. But we cannot get a hold of the nw ex-husband. He is not answering calls, texts or emails and is extremely upset by the divorce and blames everyone in the group. Other than learning my lesson in going in on these kinds of deals, what are my options. Is there a way we can sell the house without his signature? Myself and one of the other partners who owns 25% are the primaries on the mortgage. Anyone have any suggestions or ideas on how we can still sell this house?

Before sending an attorney to try and force the sale maybe try and ask the guy for lunch or something and see how he is doing? It appears looking from the outside he was the odd man out in the divorce so yes he will hold a grudge.

Try fixing the relationship before forcing him to sell as most likely he would not sell in spite because of what happened

You should contact a few attorneys and vet out the one who seems to have the most knowledge/experience with cotenancy disputes. California courts have a legal process whereby the court can force a sale of co-owned property where the cotenants are disputing (common in divorces and family disputes with co-owned property). It's costly and time consuming, but may be your only practical option to sell the property depending on the situation.